Various formation evaluation (FE) tools are used in hydrocarbon exploration and production to measure properties of geologic formations during or shortly after the excavation of a borehole. The properties are measured by formation evaluation tools and other suitable devices, which are typically integrated into a bottom hole assembly (BHA).
Some FE tools include antennas that are used during FE operations, such as logging-while-drilling (LWD) and geosteering operations. Examples of such antennas include so-called “slot” design antennas, such as “Z-type” antennas (“Z-antennas”) typically used in multi-frequency and multi-spacing propagation resistivity (“MPR”) tools and “X-type” antennas (“X-antennas”) typically used in azimuth propagation resistivity (“APR”) tools.
Current LWD antennas require a minimum slot length in order to generate a sufficiently strong signal, and thus impact space requirements and sizes of associated downhole tools. Furthermore, the lengths of such antennas make it infeasible to incorporate differing types of tools, such as MPR and APR tools, together to improve LWD operations such as geosteering operations.